1. Field of the Invention
The present invention relates to an optically-anisotropic film usable in various displays (for example, transmissive-type and reflective/transmissive-type liquid-crystal display devices for use in OA appliances and mobile terminals) and pickups for optical discs, and to a liquid-crystal display device such as transmissive-type and reflective/transmissive-type devices.
2. Related Art
λ/4 plates have a great many applications, and are already used in reflective-type LCDs, pickups for optical discs and PS conversion devices. However, most of so-called λ/4 plates achieve λ/4 within a specific wavelength range. For achieving λ/4 within a broader wavelength range, proposed is a technique of laminating two optically-anisotropic polymer films (for example, see Japanese Patent Application Laid-Open Publication Nos. 10-68816 and 10-90521). Also proposed is a retardation plate constructed by laminating a polymer film having a retardation of λ/4 and a polymer film having a retardation of λ/2 in such a manner that their slow axes cross each other (for example, see Japanese Patent Application Laid-Open Publication No. 10-68816). Further proposed is a retardation plate constructed by laminating at least two retardation plates having a retardation of from 160 to 320 nm in such a manner their slow axes are not in parallel but cross at an angle not at a right angle (for example, see Japanese Patent Application Laid-Open Publication No. 10-90521). These retardation plates achieve λ/4 within a broad wavelength range, comprising two polymer films. On the other hand, disclosed is a thinned, broad-band λ/4 plate constructed by laminating plural optically-anisotropic layers formed of liquid-crystalline molecules (for example, see Japanese Patent Application Laid-Open Publication Nos. 2001-4837 and 2000-321576).